The present invention relates to an actuation and supply unit, particularly for auxiliary actuators suitable to actuate complementary fixtures and/or tools in die-forming presses.
Die-forming presses associated with other complementary fixtures or tools which complete the machining process are currently widely used.
Merely by way of example, the presses can be associated with blanking machines for trimming the edge flash of the die and with punches or other blanking tools used to form one or more holes.
In particular, presses associated with other fixtures or tools are provided with a main actuator which actuates the press and with which other auxiliary actuators are associated. The auxiliary actuators are usually independent and are adapted to actuate the fixtures or tools related to the complementary machining processes.
In particular, auxiliary actuators are currently constituted, in a first type of construction, by a mechanical cam which is actuated, by means of kinematic systems, by the same actuation as the press.
This embodiment, however, entails considerable problems in terms of bulk and complexity of construction.
In a second embodiment, the press works like a pump for the auxiliary actuators, which in this case are constituted by hydraulic pistons.
However, manufacturing and production practice has shown that this solution entails, in high-tonnage presses, an imbalance of the die; moreover, it is evident that the complementary machining operations can be performed only during the return step of the pressing cycle, i.e., when the press is rising, but this is exactly the step in which the press absolutely cannot act as a pump, since it is in the discharge step.
Hydraulic plants, including actuations for auxiliary actuators and hydraulic power accumulators are known, for example, from the prior documents CH-A-354 562, EP-A-0 661 125, EP-A-022 661, DEA-26 20 016 FR-A-1 436 264.